We continue to study the relevance of the heterophile transplantation antigen (HTA) in human transplantation. In the coming year we hope to: (1) Continue to evaluate the benefit of pretransplant indirect matching for HT-A in the donor and recipient. (2) Determine the relationship between the HTA system and the HLA-DRw. (3) Study the number of specificities detected by anti-HTA sera.